Department of Mechanical and Materials Engineering, Queen's University, McLaughlin Hall, Room 205, Kingston, ON K7L 3N6, Canada.
Ann Biomed Eng. 2010 Apr;38(4):1672-82. doi: 10.1007/s10439-010-9917-5. Epub 2010 Jan 20.
Mechanical stimulation of engineered cartilage constructs is a commonly applied method used to accelerate tissue formation and improve the mechanical properties of the developed tissue. While the effects of compression and shear have been widely studied, the effect of tension has received relatively little attention. As articular cartilage in vivo is subjected to a degree of static tension (pre-tension) even in the absence of externally applied loads, the purpose of this study was to investigate the effect of intermittent static biaxial tensile strains (BTS) on chondrocyte metabolism and resultant tissue formation. Using a custom-design loading fixture to apply BTS, the optimal conditions for stimulating extracellular matrix synthesis were under average magnitudes of 3.8% radial and 2.1% circumferential tensile strains for 30 min. Tissue constructs subjected to tensile strain stimulation 3 times/week for a period of 4 weeks displayed increased thickness (35 +/- 18%) and proteoglycan content (22 +/- 7%) without an associated change in mechanical properties. In contrast, constructs stimulated daily over the same time period exhibited negligible effects in terms of ECM accumulation suggesting that the frequency of stimulation needs to be precisely controlled. The results of this study demonstrate that while tension can be used as potential biomechanical stimulus to improve tissue formation, further optimization of this process needs to be conducted to improve ECM accumulation and tissue mechanical properties after long-term exposure to tensile stimuli.
工程化软骨构建体的机械刺激是一种常用的方法，用于加速组织形成并改善所开发组织的机械性能。虽然压缩和剪切的影响已经得到了广泛的研究，但张力的影响相对较少受到关注。由于关节软骨在体内即使在没有外部施加的负荷的情况下也会受到一定程度的静态张力（预张力），因此本研究的目的是研究间歇静态双轴拉伸应变（BTS）对软骨细胞代谢和随后的组织形成的影响。使用定制设计的加载夹具施加 BTS，刺激细胞外基质合成的最佳条件是平均径向 3.8%和周向 2.1%的拉伸应变，持续 30 分钟。每周接受拉伸应变刺激 3 次，持续 4 周的组织构建体显示出厚度增加（35 +/- 18%）和糖胺聚糖含量增加（22 +/- 7%），而机械性能没有变化。相比之下，在相同时间内每天受到刺激的构建体在 ECM 积累方面表现出可忽略的效果，这表明需要精确控制刺激的频率。这项研究的结果表明，虽然张力可以用作改善组织形成的潜在生物力学刺激，但需要进一步优化该过程，以在长期暴露于拉伸刺激后改善 ECM 积累和组织机械性能。
